Nikola Tesla - Free-Energy Devices

UNIPOLAR GENERATORS. 478indicated by the full or dotted lines, Fig. 295.The difference ofpotential between a point on the shaft and a point on the peripherywill remain unchanged, in sign as well as in amount. Theonly difference will be that the resistance of the disc will be augmentedand that there will be a greater fall of potential from apoint on the shaft to a point on the periphery when the same currentis traversing the external circuit. But since the current isforced to follow the lines of subdivision, we see that it will tendeither to energize or de-energize the field, and this will depend,other things being equal, upon the direction of the lines of subdivision.If the subdivision be as indicated by the full lines inFig. 295, it is evident that if the current is of the same directionas before, that is,from centre to periphery, its effect will be tostrengthen the field magnet; whereas, if the subdivision be as in-FIG. 295. FIG. 296.dicated by the dotted lines, the current generated will tend toweaken the magnet. In the former case the machine will becapable of exciting itself when the disc is rotated in the directionof arrow D ;in the latter case the direction of rotation must bereversed. Two such discsmay be combined, however,as indicated,the two discs rotatingin opposite fields, and in the sameor opposite direction.Similar disposition may, of course, be made in a type ofmachine in which, instead of a disc, a is cylinder rotated. Insuch unipolar machines, in the manner indicated, the usual fieldcoils and poles may be omitted and the machine may be made toconsist only of a cylinder or of two discs enveloped by a metalcasting.Instead of subdividing the disc or cylinder spirally,as indicatedin Fig. 295, it is more convenient to interpose one or more turns